With the development of communication technology, antenna arrays have been utilized for data transmission. Nowadays, antenna arrays have been employed in LTE (Long-Term Evolution) technology. For example, diversity communication or multiplex communication has been used in LTE antenna arrays.
The number of antennas in an antenna array may be more than 100. The communication of antenna arrays can be applied to frequency-division multiplexing mode and time-division duplexing mode. In the frequency-division multiplexing mode, feedback loading will be caused by massive antennas. Thus, it is important to reduce loading in the multiplexing mode.